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Date:   Sun, 3 Oct 2021 02:29:13 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Huacai Chen <chenhuacai@loongson.cn>
Cc:     Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH V4 14/22] LoongArch: Add signal handling support
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References: <20210927064300.624279-1-chenhuacai@loongson.cn>
 <20210927064300.624279-15-chenhuacai@loongson.cn>
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On Mon, Sep 27, 2021 at 02:42:51PM +0800, Huacai Chen wrote:
> This patch adds signal handling support for LoongArch.

No matter what you get in regs[4] after sys_rt_sigreturn(),
you should *NOT* treat it as restartable.  IOW, you need to set
regs[0] to 0 in there (or in restore_sigcontext()).  See e.g.
653d48b22166 for details of similar bug on arm.